Conventional right-circular cylindrical resonant cavities have several electromagnetic modes. One mode of typical interest is the TE.sub.011 mode. This mode has the electric field flowing circumferentially, which implies that no electric currents cross a joint if, for example, the end walls are removed. This type of electric flow is important as it allows the replacement of the end walls with other materials and measures surface resistance without concern about accounting for losses due to electric currents crossing a joint. Unfortunately, the TE.sub.011 mode is degenerate with a TM.sub.111 mode, which does in fact have currents that flow across joints. For right circular cylinders these two modes can be separated with a mode separator, i.e., a notch in the bottom of the cavity. Such a notch perturbs the two modes such that the TE.sub.011 mode is separated in frequency from the TM.sub.111 mode. This result is easily seen on the transmission curve of the cavity. While such a system has the desired concomitant circumferential electric field, the design, in particular the dimensions, of a right-circular cylindrical cavity is generally unsuitable for coating with superconductive materials, especially high temperature superconductive materials. It has become highly desirable to coat microwave cavities with superconductive materials, especially high temperature superconductive materials, so as to increase the quality factor, i.e., the Q-value, of the cavity as well as the performance of the cavity.
Accordingly, it is an object of this invention to provide a microwave cavity having a geometry adapted for subsequent coating by a superconductive material, preferably a high temperature superconductive material.
Another object of this invention is to provide a microwave cavity having a geometry design wherein the TE.sub.011 and TM.sub.111 modes are separated without the need for a mode separator.
It is a still further object of this invention to provide a microwave cavity having its interior surfaces coated with a superconductive material, preferably a high temperature superconductive material.